diff --git a/scripts/final_grade_options.sh-subr b/scripts/final_grade_options.sh-subr
index a200dc9a4..2a6eba637 100644
--- a/scripts/final_grade_options.sh-subr
+++ b/scripts/final_grade_options.sh-subr
@@ -1,5 +1,5 @@
 #---------------------------------------------------------------------------#
-# Copyright (C) 1998-1999 The University of Melbourne.
+# Copyright (C) 1998-2000 The University of Melbourne.
 # This file may only be copied under the terms of the GNU General
 # Public License - see the file COPYING in the Mercury distribution.
 #---------------------------------------------------------------------------#
@@ -38,4 +38,14 @@ case $stack_trace,$require_tracing,$use_minimal_model in
 		use_trail=true ;;
 esac
 
+#
+# --high-level-code disables the use of low-level gcc extensions
+#
+case $highlevel_code in true)
+	non_local_gotos=false
+	asm_labels=false
+	global_regs=false
+	;;
+esac
+
 #---------------------------------------------------------------------------#
diff --git a/scripts/parse_grade_options.sh-subr b/scripts/parse_grade_options.sh-subr
index 7fedd4291..1916d1b84 100644
--- a/scripts/parse_grade_options.sh-subr
+++ b/scripts/parse_grade_options.sh-subr
@@ -1,5 +1,5 @@
 #---------------------------------------------------------------------------#
-# Copyright (C) 1997-1999 The University of Melbourne.
+# Copyright (C) 1997-2000 The University of Melbourne.
 # This file may only be copied under the terms of the GNU General
 # Public License - see the file COPYING in the Mercury distribution.
 #---------------------------------------------------------------------------#
@@ -20,14 +20,14 @@
 #---------------------------------------------------------------------------#
 
 	--high-level-code)
-		high_level_code=true ;;
+		highlevel_code=true ;;
 	--no-high-level-code)
-		high_level_code=false ;;
+		highlevel_code=false ;;
 
 	--high-level-data)
-		high_level_data=true ;;
+		highlevel_data=true ;;
 	--no-high-level-data)
-		high_level_data=false ;;
+		highlevel_data=false ;;
 
 	--gcc-nested-functions)
 		gcc_nested_functions=true ;;
@@ -148,9 +148,9 @@
 		# may also require changes to all the files indicated by
 		# runtime/mercury_grade.h.
 
-		high_level_code=false
+		highlevel_code=false
 		gcc_nested_functions=false
-		high_level_data=false
+		highlevel_data=false
 		asm_labels=false
 		non_local_gotos=false
 		global_regs=false
@@ -174,81 +174,81 @@
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=false
-					high_level_code=true
+					highlevel_code=true
 					gcc_nested_functions=false
-					high_level_data=true
+					highlevel_data=true
 					;;
 				hlc)
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=false
-					high_level_code=true
+					highlevel_code=true
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				hl_nest)
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=false
-					high_level_code=true
+					highlevel_code=true
 					gcc_nested_functions=true
-					high_level_data=true
+					highlevel_data=true
 					;;
 				hlc_nest)
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=false
-					high_level_code=true
+					highlevel_code=true
 					gcc_nested_functions=true
-					high_level_data=false
+					highlevel_data=false
 					;;
 				asm_fast)
 					asm_labels=true
 					non_local_gotos=true
 					global_regs=true
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				asm_jump)
 					asm_labels=true
 					non_local_gotos=true
 					global_regs=false
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				fast)
 					asm_labels=false
 					non_local_gotos=true
 					global_regs=true
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				jump)
 					asm_labels=false
 					non_local_gotos=true
 					global_regs=false
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				reg)
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=true
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 				none)
 					asm_labels=false
 					non_local_gotos=false
 					global_regs=false
-					high_level_code=false
+					highlevel_code=false
 					gcc_nested_functions=false
-					high_level_data=false
+					highlevel_data=false
 					;;
 
 				par)